1. Field of Invention
The invention relates to a lighting system provided with a light-emitting panel.
The invention also relates to a display device provided with said lighting system.
2. Description of Related Art
Edge lighting systems are used inter alia as backlighting systems in (picture) display devices, for example for TV sets and monitors. Such lighting systems are particularly suitable for use as backlights for non-emissive displays such as liquid crystal display devices, also referred to as LCD panels, which are used in (portable) computers or (cordless) telephones.
Said display devices usually comprise a substrate provided with a regular pattern of pixels which are each controlled by at least one electrode. The display device utilizes a control circuit for achieving a picture or a datagraphical display in a relevant field of a (picture) screen of the (picture) display device. The light originating from the backlight in an LCD device is modulated by means of a switch or modulator, various types of liquid crystal effects being used. In addition, the display may be based on electrophoretic or electromechanical effects.
Such lighting systems are also used as luminaires for general lighting purposes or for shop lighting, for example shop window lighting or lighting of (transparent or semi-transparent) plates of glass or of (transparent) plates of synthetic resin on which items, for example jewelry, are displayed. Such lighting systems are further used as window panes, for example for causing a glass wall to radiate light under certain conditions, or to reduce or block out the view through the window by means of light. A further alternative application is the use of such lighting systems for illuminating advertising boards.
In the lighting systems mentioned in the opening paragraph, the light source used usually comprises a plurality of optoelectronic elements, also referred to as electro-optical elements, for example electroluminescent elements, such as light-emitting diodes (LEDs). These light sources are usually provided in the vicinity of or tangent to a light-transmitting edge surface of the light-emitting panel, in which case light originating from the light source is incident on the light-transmitting edge surface during operation and distributes itself in the panel.
A lighting system for illuminating an LCD panel is known from U.S. Pat. No. 5,921,652. The light source used is formed by light-emitting diodes (LEDs) which couple light into a light-emitting panel, also referred to as light pipe, via a so-called light transition area. The light is mixed in said light transition area.
A lighting system of the above type occupies too much space.